Electric water heater



May 16, 1950 1 F. GRAVES I 2,507,902

ELECTRIC WATER HEATER Filed Aug. 2, 1948 HIS ATTORNEYS.

Patented May 16, 1950 UNITED STATES PATENT OFFICE ELECTRIC WATER HEATER Frederick Graves, St. Louis, Mo.

Application August 2, 1948, Serial No. 42,098

(Cl. 21S-39) 6 Claims.

This invention relates to water heaters of the type shown in my copending application Serial No. 608,776, now United States Patent No. 2,446,367.

The principal object of the invention is to provide in the main reservoir of the heater, a dead water well which surrounds the lower portion of the enclosed heating unit and insulates the heated water owing therethrough from the cooler water in said reservoir adjacent to the cold water inlet thereof.

Another object of the invention is to provide for suspending said enclosed heating unit and well and wiring within the reservoir and for their insertion and removal in assembled relation.

The invention consists in the electric water heater and in the parts and combinations and arrangements of parts hereinafter described and claimed.

The accompanying drawing, which forms part of this specification and wherein like symbols refer to like parts wherever they occur, is a central vertical longitudinal section through an electric lwater heater embodying my invention.

AIn the accompanying drawing my invention is shown embodied in an electric water heater comprising a closed upright cylindrical reservoir A, having a cold water inlet I near the lower end thereof and a closure plate 3 at the top thereof, and a relatively long and narrow central cylindrical electric heating unit B enclosed in said :reservoir concentric therewith and spaced from the side, top and bottom thereof. vSurrounding the heating unit B concentric therewith and closely adjacent thereto is a cylindrical tube or shell C having a closed lower end 4 `spaced below the lower end of said unit and above the bottom of the reservoir A and having an open upper end extending slightly above the upper end of said unit. Thus, the intermediate'casing C cooperates with heating unit B to form therebetween a narrow annular conduit or passageway 5 which leads upwardly from the chamber 6 between the vertically spaced bottoms of said casing and said heating unit and opens into the reservoir AA at the open upper end of said casing. A central vertical tubular hot water outlet conduit 'I l extends upwardly throuh the heating unit B from the chamber 6 therebelow and through the top cover plate 3 of the reservoir A. By the `arrangement described, the water enters the reservoir A through the inlet conduit I in the side thereof and iills said reservoir. The water thence flows downwardly through the annular conduit l between the heating unit B and the cylin- 2 drical shell C into the chamber B in the bottom of the latter and thence ows upwardly through the central outlet conduit 1 to the discharge end thereof.

The electric heating unit B comprisesa cylindrical casing 8 having top and bottom closure plates 9 and I0, respectively, through which the central outlet tube or conduit 'l extends. The heating element for said unit comprises a. ribbon resistance wire II that is helically wound around'a supporting core I2 of porcelain or other earthenware refractory material located in the casing 8. The core I2 has an external helical groove I3 in which the helically wound resistance wire II is seated; and the outlet tube or conduit 'I extends through an axial bore I4 provided therefor in said core. The ends of the resistance wire I I extend through the ends of the core I2.

Extending through the top of the reservoir A and the heating unit casing 8 is a wiring conduit I5 for one lead I1 of an electric circuit for energizing the resistance coil I I and extending downwardly through bottom I0 of casing 8 and thence through low end 4 of cylindrical shell C is a simil lar wiring conduit I5a for the other lead I'Ia of said circuit.

In accordance with the present invention, the above heater is provided with a cylindrical tube or shell having a closed bottom and open upper end. The shell D surrounds the shell C and is spaced from the side and bottom thereof and extends upwardly along with shell C for the greater portion of its length and provides a dead or still water chamber or well I9 which surrounds the entire lower `portion of the shell D and opens atiitsupper end into the 'interior of said reservo r.

The Well forming casing D is spaced from casing C by a series of circumferentially spaced radially disposed spacers 22 that span the annular space between said casings and are welded or otherwise rigidlysecured thereto. The wiring conduit I5a extends downwardly into the space between the bottoms of the casing C and the sides formingshell D and thence upwardly between said casing and shell and then through the top cover plate of the reservoir A. i

As shown in the drawing, a suitable relief valve 2| is located on outlet conduit 1 between cover plate 3 of reservoir A and top closure plate 9 of heating unit B. Y

The cylindrical well casing D, the shell C, and heating unit B are suspended from top cover plate of reservoir A bythe outlet conduit I and wiring conduits I5 and I5a, all of which are secured to said top by means of annular welds 24. Annular welds 21 also secure the wiring conduits I and I5a and outlet conduit 'I to the top closure plate 9 and the bottom closure plate I0 of said heating unit. These welds all provide waterproof joints between the parts connected thereby and they also maintain the parts in proper spaced relation.

When the electric heater unit B is turned on and the water is flowing therethrough in the manner herelnbefore described, the refractory core I2 is heated to a high degree by the resistance wire I I helically coiled therearound and the heat is transmitted through the water tight coil and core enclosing casing 8 to the thin annular stream of water flowing downwardly through the narrow annular conduit 5 between the spaced sides of the heater unit casing 8 and the intermediate casing C into the chamber 6. The water thence il-ows upwardly from the chamber 6 through the central outlet conduit 'I where it is again heated by the heated refractory coil supporting core I2. Thus, the flowing water is continuously and rapidly heated during its passage through the electric heater. If the water is not in motion, the relief valve 2l in the outlet conduit 'l allows the water to circulate by its own expansion back into the reservoir.

During the operation of the heater, the earthenware refractory core I2 is heated to incandescence by the heating coil II and, after the heater is turned off, this extremely hot core continues to give off heat ln the form of radiant energy which serves to keep the water in the storage chamber at a fairly high temperature for several hours. If, within this period of time, the heater is again turned on, an initial supply of hot water is provided until the heater again becomes effective to heat the ilowing water. The cylindrical shell D provides a well in which there is little, if any, circulation of water. Hence the water therein is at a temperature only slightly below the temperature of the water in the passageway 5, thereby serving to insulate the water in saidpassageway from the colder `water in the cold water inlet area of the reservoir A and thus increasing the eiliciency of the heater. The cylindrical well shell D, the intermediate casing C, the heating unit B and the wiring conduits I5 and I5a are all suspended from the top cover plate 3 of the reservoir A and are all adapted for insertion in and removal from said reservoir in assembled relation.

Obviously', the hereinbefore described electri water heater admits of considerable modification without departing from the invention. Therefore, I do not wish to be limited to the precise arrangements shown and described.

What I claim is: 1. An electric water heater comprising a reservoir having an opening at the upper end thereof, a closure for said opening, a tubular casing located in said reservoir and spaced from the side, top, and bottom and connected only to the top thereof, said tubular casing being closed at its lower end and open at its upper end, an electric heating unit located in said tubular casing and spaced therefrom to form a chamber at the closed lower end thereof and a passageway leading from said chamber and opening intoy said reservoir at said upper end of said casing, a central outlet tube passing through said electric heating unit and opening at its lower end into said chamber and extending exteriorly of the said reservoir at the upper end thereof, and two wiring conduits leading upwardly from the upper and lower ends, respectively, of said heating unit through the upper end of said reservoir, said tubular casing, heating unit, wiring conduits, and outlet tube being connected together for unit insertion in and removal from said reservoir through the opening in the upper end thereof.

2. An electric water heater comprising a reservoir having an inlet in the lower portion thereof, a cylindrical well located in said reservoir and spaced from the side and bottom thereof,

said cylindrical well being closed at its lower end and open at its upper end, a tubular casing located within said well concentric therewith,

said tubular casing being closed at its lower end and `open at vits upper end, an electric heating unit located in said tubular casing and spaced therefrom to form a chamber at the closed lower end thereof and a passageway leading from said chamber and opening into said reservoir at said upper end of said casing, and a central outlet tube passing through said electric heating unit and opening at its lower end into said chamber and extending exteriorly of said reservoir at the upper end thereof.

3. An electric water heater comprising a reservoir having an inlet adjacent to the lower end thereof, a cylindrical well located in said reservoir and spaced from the side and bottom thereof, said cylindrical well being closed at its lower end and open at its upper end, a tubular casing located within said well and concentric therewith, said tubular casing being closed at its lower end and open at its upper end, an electric heating unit located in said tubular casing and spaced therefrom to form a chamber at the closed lower end thereof and a passageway leading from said chamber and opening into said reservoir at said upper end of said casing, a central outlet tube passing through said electric heating unit and opening at its lower end into said chamber and extending exteriorly of said reservoir at the upper end thereof, and two wiring conduits leading upwardly from the upper and lower ends, respectively, of said heating unit through the upper end of said reservoir, said cylindrical well, tubular casing, heating unit, wiring conduits, and outlet tube being connected together for insertion in and removal from said reservoir through the opening in the upper end thereof.

4. An electric water heater comprising a closed cylindrical reservoir having an opening at the upper end thereof, a closure for said opening, a, cylindrical casing located inv said reservoir concentric therewith and spaced from the side, top. and bottom and connected only tothe top there.- of, said cylindrical casing being closed at its lower end and open at its upper end, a cylindrical electric heating unit located in said tube concentric therewith and spaced therefrom to form a chamber at the closed lowel` end thereof and an annular conduit leading from said chamberand open,.- ing into said reservoir at said open upper end of said casing, an outlet tube passing axially through saidelectric heating. unit and opening at its lower end into said chamber and extending exteriorly of the said reservoir at the upper end thereof, and two wiring conduits leading upwardly from the upper and lower ends, respectively, of said heating unit through the upper end of said reservoir, said cylindrical casing, heating unit, wiring conduits, and outlet tube being connected together for unit insertion in and removal from said reservoir through the opening .75 inthe upper end thereof.

5. An electric water heater comprising a closed cylindrical reservoir having an inlet in the lower portion thereof, a cylindrical well located in said reservoir and spaced from the side and bottom thereof, said cylindrical well being closed at its lower end and open at its upper end, a cylindrical casing located within said well concentric therewith, said cylindrical casing being closed at its lower end and open at its upper end, a cylindrical electric heating unit located in said tube concentric therewith and spaced therefrom to form a chamber at the closed lower end thereof and an annular conduit leading from said chamber and opening into said reservoir at said open upper end of said casing, and an outlet tube passing axially through said electric heating unit and opening at its lower end into said chamber and extending exteriorly of said reservoir at the upper end thereof.

6. An electric water heater comprising a closed cylindrical reservoir having an inlet adjacent to the lower end thereof, a cylindrical well located in said reservoir and spaced from but not attached to the side and bottom thereof, said cylindrical well being closed at its lower end and open 25 Number at its upper end, a cylindrical casing located within said well and concentric therewith, said tubular casing being closed at its lower end and open at its upper end, a cylindrical electric heating unit located in said tube concentric therewith and spaced therefrom to form a chamber at the closed lower end thereof and an annular conduit leading from said chamber and opening into said reservoir at said open upper end of said casing, an outlet tube passing axially through said electric heating unit and opening at its lower end into said chamber and extending exteriorly of said reservoir at the upper end thereof, and two wiring conduits leading upwardly from the upper and lower ends, respectively, of said heating unit through the upper end of said reservoir, said cylindrical well, cylindrical casing, heating unit, wiringconduits, and outlet tube being connected together for insertion in and removal from said reservoir through the opening in the upper end thereof.

FREDERICK GRAVES.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Name Date 1,174,443 Quain Mar. 7, 1916 1,519,395 Clench Dec. 16, 1924 2,446,367 Graves Aug. 3. 1948 

